Java,runfiles: add Runfiles.getEnvVars()

The new method lets Java programs export the
RUNFILES_* environment variables for subprocesses,
in case those subprocesses are other Bazel-built
binaries that also need runfiles.

See https://github.com/bazelbuild/bazel/issues/4460

Change-Id: I05c0b84db357128bc15f21a167a0d92e8d17599c

Closes #5016.

Change-Id: I66ca5c44067a7353b8de180a64f20c8352e3c9ec
PiperOrigin-RevId: 193013289

3 files changed, 62 insertions, 42 deletions

diff --git a/src/test/py/bazel/runfiles_test.py b/src/test/py/bazel/runfiles_test.py
index 21ed5fd855..fb2b0e180f 100644
--- a/src/test/py/bazel/runfiles_test.py
+++ b/src/test/py/bazel/runfiles_test.py
@@ -31,50 +31,12 @@ class RunfilesTest(test_base.TestBase):
     self.assertIn("building runfiles is not supported on Windows",
                   "\n".join(stderr))
 
-  def testJavaRunfilesLibraryInBazelToolsRepo(self):
-    for s, t in [
-        ("WORKSPACE.mock", "WORKSPACE"),
-        ("foo/BUILD.mock", "foo/BUILD"),
-        ("foo/Foo.java", "foo/Foo.java"),
-        ("foo/datadep/hello.txt", "foo/datadep/hello.txt"),
-    ]:
-      self.CopyFile(
-          self.Rlocation(
-              "io_bazel/src/test/py/bazel/testdata/runfiles_test/" + s), t)
-
-    exit_code, stdout, stderr = self.RunBazel(["info", "bazel-bin"])
-    self.AssertExitCode(exit_code, 0, stderr)
-    bazel_bin = stdout[0]
-
-    exit_code, _, stderr = self.RunBazel(["build", "//foo:runfiles-java"])
-    self.AssertExitCode(exit_code, 0, stderr)
-
-    if test_base.TestBase.IsWindows():
-      bin_path = os.path.join(bazel_bin, "foo/runfiles-java.exe")
-    else:
-      bin_path = os.path.join(bazel_bin, "foo/runfiles-java")
-
-    self.assertTrue(os.path.exists(bin_path))
-
-    exit_code, stdout, stderr = self.RunProgram(
-        [bin_path], env_add={"TEST_SRCDIR": "__ignore_me__"})
-    self.AssertExitCode(exit_code, 0, stderr)
-    if len(stdout) != 2:
-      self.fail("stdout: %s" % stdout)
-    self.assertEqual(stdout[0], "Hello Java Foo!")
-    six.assertRegex(self, stdout[1], "^rloc=.*/foo/datadep/hello.txt")
-    self.assertNotIn("__ignore_me__", stdout[1])
-    with open(stdout[1].split("=", 1)[1], "r") as f:
-      lines = [l.strip() for l in f.readlines()]
-    if len(lines) != 1:
-      self.fail("lines: %s" % lines)
-    self.assertEqual(lines[0], "world")
-
-  def _AssertPythonRunfilesLibraryInBazelToolsRepo(self, family, lang_name):
+  def _AssertRunfilesLibraryInBazelToolsRepo(self, family, lang_name):
     for s, t in [
         ("WORKSPACE.mock", "WORKSPACE"),
         ("foo/BUILD.mock", "foo/BUILD"),
         ("foo/foo.py", "foo/foo.py"),
+        ("foo/Foo.java", "foo/Foo.java"),
         ("foo/datadep/hello.txt", "foo/datadep/hello.txt"),
         ("bar/BUILD.mock", "bar/BUILD"),
         ("bar/bar.py", "bar/bar.py"),
@@ -132,7 +94,10 @@ class RunfilesTest(test_base.TestBase):
       i += 2
 
   def testPythonRunfilesLibraryInBazelToolsRepo(self):
-    self._AssertPythonRunfilesLibraryInBazelToolsRepo("py", "Python")
+    self._AssertRunfilesLibraryInBazelToolsRepo("py", "Python")
+
+  def testJavaRunfilesLibraryInBazelToolsRepo(self):
+    self._AssertRunfilesLibraryInBazelToolsRepo("java", "Java")
 
   def testRunfilesLibrariesFindRunfilesWithoutEnvvars(self):
     for s, t in [
diff --git a/src/test/py/bazel/testdata/runfiles_test/foo/BUILD.mock b/src/test/py/bazel/testdata/runfiles_test/foo/BUILD.mock
index 04fc23ebac..48d3108f67 100644
--- a/src/test/py/bazel/testdata/runfiles_test/foo/BUILD.mock
+++ b/src/test/py/bazel/testdata/runfiles_test/foo/BUILD.mock
@@ -15,6 +15,8 @@ java_binary(
     srcs = ["Foo.java"],
     data = [
         "datadep/hello.txt",
+        "//bar:bar-py",
+        "//bar:bar-java",
     ],
     main_class = "Foo",
     deps = ["@bazel_tools//tools/runfiles:java-runfiles"],
diff --git a/src/test/py/bazel/testdata/runfiles_test/foo/Foo.java b/src/test/py/bazel/testdata/runfiles_test/foo/Foo.java
index 0e9f5cfcd0..44a01847ce 100644
--- a/src/test/py/bazel/testdata/runfiles_test/foo/Foo.java
+++ b/src/test/py/bazel/testdata/runfiles_test/foo/Foo.java
@@ -13,13 +13,66 @@
 // limitations under the License.
 
 import com.google.devtools.build.runfiles.Runfiles;
+import java.io.BufferedReader;
+import java.io.File;
 import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
+import java.util.concurrent.TimeUnit;
 
 /** A mock Java binary only used in tests, to exercise the Java Runfiles library. */
 public class Foo {
-  public static void main(String[] args) throws IOException {
+  public static void main(String[] args) throws IOException, InterruptedException {
     System.out.println("Hello Java Foo!");
     Runfiles r = Runfiles.create();
     System.out.println("rloc=" + r.rlocation("foo_ws/foo/datadep/hello.txt"));
+
+    for (String lang : new String[] {"py", "java"}) {
+      String path = r.rlocation(childBinaryName(lang));
+      if (path == null || path.isEmpty()) {
+        throw new IOException("cannot find child binary for " + lang);
+      }
+
+      ProcessBuilder pb = new ProcessBuilder(path);
+      pb.environment().putAll(r.getEnvVars());
+      if (isWindows()) {
+        pb.environment().put("SYSTEMROOT", System.getenv("SYSTEMROOT"));
+      }
+      Process p = pb.start();
+      if (!p.waitFor(3, TimeUnit.SECONDS)) {
+        throw new IOException("child process for " + lang + " timed out");
+      }
+      if (p.exitValue() != 0) {
+        throw new IOException(
+            "child process for " + lang + " failed: " + readStream(p.getErrorStream()));
+      }
+      System.out.printf(readStream(p.getInputStream()));
+    }
+  }
+
+  private static boolean isWindows() {
+    return File.separatorChar == '\\';
+  }
+
+  private static String childBinaryName(String lang) {
+    if (isWindows()) {
+      return "foo_ws/bar/bar-" + lang + ".exe";
+    } else {
+      return "foo_ws/bar/bar-" + lang;
+    }
+  }
+
+  private static String readStream(InputStream stm) throws IOException {
+    StringBuilder result = new StringBuilder();
+    try (BufferedReader r =
+        new BufferedReader(new InputStreamReader(stm, StandardCharsets.UTF_8))) {
+      String line = null;
+      while ((line = r.readLine()) != null) {
+        line = line.trim(); // trim CRLF on Windows, LF on Linux
+        result.append(line).append("\n"); // ensure uniform line ending
+      }
+    }
+    return result.toString();
   }
 }